Marrowstone Island, WA
EPA Region 10 received a petition from the Marrowstone Island Community Association on August 27, 1991, which requested EPA to designate Marrowstone Island as a Sole Source Aquifer. The population of the Island varies by season, from about 600 in the winter, to about 1,300 during a peak summer weekend.
EPA's review of the petition and other data determined that:
- The Marrowstone Island Aquifer System supplies approximately 98 percent of the drinking water to persons living on the island;
- As the area's principal source of drinking water, contamination of the aquifer system would create a significant hazard to public health;
- The boundary encompasses the entire island and includes all potable water-bearing geologic units underlying the Island;
Water quality studies have discovered elevated chloride concentrations that indicate seawater intrusion is occurring in the fresh water aquifer system underlying the Island. This intrusion of seawater is the result of increased pumping of the aquifers, which is attributable to the increase in Island population.
- There are no feasible alternative source(s) of drinking water which could replace the aquifer system, should it become contaminated.
Designation (Federal Register - as proposed)
Sole Source Aquifer Maps
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